1. Field of the Invention
This invention relates to metallized multilayered packaging films utilized in the packaging of food or non-food products or in the formation of bags, cartons or pouch-type containers designed to hold such products.
2. Background Information Including Description of Related Art
Metallized plastic films having a polyolefin core layer, e.g., of oriented isotactic polypropylene homopolymer (OPP), have been widely utilized in food and non-food packaging and containers because of their desirable properties, e.g., resistance to the transmission of moisture, air, deleterious flavors and the like, as well as their excellent mechanical properties. However, a disadvantage of many of these films is the difficulty of covering the metal layer to protect the metal from scratches and obtain high seal strength. Thus, any means sufficient to overcome these difficulties would allow for the production of metallized films much better suited for packaging applications.
The following references may be pertinent to the claimed invention.
U.S. Pat. No. 4,345,005, issued Aug. 17, 1982 to All et al., discloses oriented polypropylene film having enhanced adhesion to metallized coatings produced by coextruding a film substrate having a polypropylene homopolymer core layer and a propylene-ethylene copolymer outer layer, biaxially orienting the film, and corona discharge treating the outer layer. A metal coating may then be deposited on the corona discharge treated layer.
U.S. Pat. No. 4,692,380, issued Sep. 8, 1987 to Reid, discloses metallized biaxially oriented polypropylene films produced by coextruding polypropylene homopolymer containing a fatty acid amide slip agent as the core layer with a propylene-ethylene copolymer which forms a thin layer on one surface of the polypropylene core layer, subjecting the propylene-ethylene layer to a corona discharge treatment, and metallizing the corona-discharge treated surface.
U.S. Pat. No. 5,126,198, issued Jun. 30, 1992 to Schinkel et al., discloses heat-laminatable multilayer films comprising a polypropylene base layer and at least one additional layer containing a mixture of an ethylene/vinyl acetate copolymer and an ethylene/acrylic acid copolymer.